[en] Lanreotide (D-β-Nal-Cys-Try-D-Trp-Lys-Val-Cys-Thr-NH2) is a new somatostatin analogue. It can bind to human somatostatin receptor (hSSTR) subtype 2 through 5 with high affinity and to hSSTR subtype 1 with low affinity. We investigate labeling condition, quality control and stability in vitro of ¹²⁵I-Lanreotide and ¹⁸⁸Re-lanreotide respectively. (A) Lanreotide is labeled with ¹²⁵I using Chloramine T. The effect of reaction condition (such as reaction time, pH value, Lanreotide amount, quantity of Chloramine T and reaction volume) on labeling yield is investigated in detail. (B) The labeling yield and radiochemical purity (RP) is measured with paper chromatography (PC) and Sep-Pak C₁₈ Cartridge. For PC method, ¹²⁵I-Lanreotide is spotted on the Whatman No.1 paper and developed in the mixture of CH₃CH₂CH₂CH₂OH and CH₃CH₂OH and NH₄OH (v/v/v=5:2:1), the Rf value of every component in the mobile phase is given in table 1. For Sep-Pak C₁₈ Cartridge methods each cartridge is washed with 10 ml of ethanol followed by 10 ml of iso-CH₃CH₂CH₂OH solution. Aliquots of 0.1 mI sample is loaded onto the cartridge, unbound peptide (sodium iodine-125) is eluted with 5 ml of 0.5mol/L sodium acetate solution, ¹²⁵I-Lanreotide is eluted with 5 mI of 95% aqueous ethanol solution. (C) The stability of ¹²⁵I-Lanreotide in vitro is investigated by labeling compound incubating for 48 hours at 37 deg. C in the 0.9% sodium chloride solution and RP is tested by PC at specific time intervals. (D) Lanreotide is labeled directly with ¹⁸⁸Re via the mixture of citrate and tartate using stannous chloride as reduced agent. The influence of reaction conditions such as pH, temperature, amount of stannous chloride, amount of Lanreotide and reaction time on labeling yield is investigated in detail. At the time, the stability in vitro quality control and animal test are evaluated